Volume-rendered images are very useful for representing 3D medical imaging datasets. Volume-rendered images are typically 2D representations of a 3D medical imaging dataset. There are currently many different techniques for generating a volume-rendered image. One such technique, ray-casting, includes projecting a number of rays through the 3D medical imaging dataset. Each sample in the 3D medical imaging dataset is mapped to a color and a transparency. Data is accumulated along each of the rays. According to one common technique, the accumulated data along each of the rays is displayed as a pixel in the volume-rendered image. In order to gain an additional sense of depth and perspective, volume-rendered images are oftentimes shaded based on a light direction. Shading may be used in order to convey the relative positioning of structures or surfaces in the volume-rendered image. The shading helps a viewer to more easily visualize the three-dimensional shape of the object represented by the volume-rendered image.
Standard volume-rendering techniques typically calculate shadows for the volume-rendered image based on a single light source. This can lead to harsh shadows and/or overly bright regions on portions of the volume-rendered image that may be distracting to viewers. It would be desirable to retain the advantages of shading while reducing the harshness of the shadows. Additionally, it has become an increasingly common practice for parents to retain prenatal images as keepsakes, specifically in the ultrasound imaging modality. This practice has led to in increased demand for volume-rendered images that are qualitatively nicer to view and that are more similar to photographs in appearance.
Therefore, for these and other reasons, a system and method for generating volume-rendered images with multiple light sources is desired.